A rebreather is a type of breathing apparatus that recycles exhaled air, allowing divers to use it multiple times. It removes carbon dioxide and adds oxygen, enabling longer underwater excursions without the need for frequent air tank refills. Rebreathers are commonly used in deep-sea diving, military operations, and underwater research. Unlike traditional scuba gear, which releases exhaled air into the water, rebreathers maintain a closed system. This makes them more efficient and reduces the noise of bubbles, which can be crucial for activities like marine biology studies or underwater photography.